Electrical apparatus



Oct. 10, 1939. E. c. wENTZ 21 5 3 ELECTR ICAL APPARATUS Filed June 16, 1957 Z6 I l WITNESSES; iNVENTOR Patented Oct. 10, 1 939 UNITED STATES PATENT OFFICE ELECTRICAL APPARATUS Edward 0. Wentz, Sharpsvllle, Pa., assignor to Westinghouse Electric 4; Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application June 16, 1937, Serial No. 148,465

8 Claims. (Cl. 175-358) ductor cable. commodating the secondary'winding coils 2 and The conventional through-type current trans- 3 that are shown connected in series with each former has a rectangular core forming a window other and with an ammeter 4. The winding legs through which the cable or primary conductor exof the core are connected by yokes 5 and 6, the tends, and is provided with secondary coils on whole core assembly constituting a rectangular two opposite legs of the rectangular core. The structure of magnetic material made up of layers secondary current output is proportional to the or laminations of magnetic steel and providing a. primary current and is measured by an ammeter central window or opening through which the priin the secondary circuit in a well known manner. mary cable or conductor I passes.

In many situations, such as where it is desir- Referring to Fig. 2, one layer or core laminaable to measure the current in different single tion is illustrated which may be constructed from u conductor cables, it is obviously a great advancorrespondingly shaped punchings 8 and 9, formtage if the transformer can be moved from one ing the winding legs, joined by punchings II and cable to another and the core can be readily I 2,forming the yokes connecting the winding legs. placed around the cable or primary conductor It will be noted that the upper yoke punching I2 without disturbing it. This has been accomis pivoted on a pin I3 near one end about which it plished in the past by removing one leg or yoke may swing from its closed or full line position of the core to enable the transformer core to be upwardly to an open or dotted line position Iii. placed around the conductor, replacing this leg The center of the pivot pin I 3 about which the or yoke after the transformer is in place and punching I2 is swung is in line with the upper end holding it in position by a clamp or spring. This of the punching 8 and inner edge of the punching g6 provision necessarily introduces two air gaps I2, and the outer end of the hinged lamination I2 into t e ma e Circuit d the performance abuts adjacent the inner edge of the punching 9 of the transformer is correspondingly poor, since when in its closed position. That is, the upper the air gaps may vary slightly. The core ends end of the punching 8 abuts against the inner or 80 m y be r n to a fiat ce to x y fit the lower edge of the punching I2 when in its closed surfaces and reduce the gap, but this has proven position, and the upper end of the punching 9 not to be very efiective, possibly because it tends aligns with the outer edge of the punching I2 to short circuit the laminations destroying the inwhen in its closed position. sulating Varnish between them. The assembly of an adjacent layer of magnetic An O j of s invention s to provide a material, as shown in Fig. 3, corresponds to that as current transf rmer, the C r Of which y be shown in Fig. 2, except that it is turned around readily placed about a cable and detached there so that the hinge or pivot pin I3 i at the other from to permit the measurement of the current end of th am connecting yoke. In Fig, 3, the therein. punchings I4, I5, I6 and I1 correspond, respec- A more spec fi Object of y ion is t e tively, to the punchings 9, I2, 8 and II. When 0 provision of a current transformer With 8 ecthe layer of magnetic material disclosed in Fig. 3 tancular Corehaving e core member consistis placed upon that disclosed in Fig. 2, so that the ing o individually hinged ons that m y windows or central rectangular openings correbe swung to closed or open positions. to provide spond. it will be noted that the ends of the several a core of substantially constant magnetic properpunchings in the adjacent layers terminate at dif- 5 ties when closed and to permit removal of the ferent parts of the magnetic circuit. For examcore from the primary conductor when open. pie, the punching I4 extends to the upper edge of Figure 1 is a perspective view showing a conthe hinged yoke punching I2 and the upper end ventional current transformer of the through of the punching 8 terminates at the lower or primary type, inner edge of the punching I2. The outer end 50 Figs. 2 and 3 are side views showing one arof the hinged punching I5 of Fig. 3 terminates rangement of alternate laminations of magnetic adjacent the punching I 4 and the punching I2 is material employed in the core of a transformer continuous at this line. The remaining edges of constructed in accordance with my invention, and the several punchings are arranged so that the Fig. 4 is a perspective view of such a trans- My invention relates to instrument transformers, and particularly to portable throughtype current transformers that are adapted to be employed to measure the current in a single conformer with the hinged laminations swung upwardly to a partially open position.

Referring to Fig. 1, the core I is rectangular in form, providing two vertical winding legs for acabutting edges of the several punchings in the u layer shown in Fig. 3 come at different parts of the magnetic circuit than those in the layer shown in Fig. 2. l

The core is made up of alternate layers corresponding to the arrangements disclosed in Figs. 2 and 3, so that the overlapping of adjacent or alternate layers of magnetic material are such that no gap exists at any point in the magnetic circuit. As one of the hinged punchings I2 is moved to its open position, it will move between the adjacent upper ends of the punchings H on opposite sides thereof and as the punching 15, that is pivoted at the right of the window as viewed in Fig. 3, is moved upwardly it will move between the upper ends of punchings 9 on opposite sides thereof. The outer end of each hinged punching l2 or IE abuts against the inner edge of a punching in the same layer 9 or I4, respectively, when in its closed position.

In Fig. 4 a transformer is shown assembled with frame members 2| and 22 attached to the upper ends of the two winding legs for supporting hinge pins l3 upon which the hinged laminations l2 and I5 are pivotally supported, the laminations I2 and I5 being disclosed in the figure as extending upwardly to indicate the manner in which the transformer is removed from a primary winding cable such as shown in Fig. l, which passes through the window between the secondary windings 2 and 3.

It will be appreciated that in the through-type current transformer core with individually hinged interleaved laminations provided by my invention, all of the joined laminations of the core structure overlap those of the adjacent layers, thus providing a structure that can consistently duplicate a high standard of accuracy of performance when successively applied to different cables, or when removed from and reapplied to, the same cable, since the usual air gaps which are of uncertain effect in the magnetic circuit between different assembling operations of the transformer have been eliminated.

It will be obvious that many modifications of the structure shown and described may be made within the spirit of my invention, and I do not wish to be limited otherwise than by the scope of the appended claims.

I claim as my invention:

1. In a laminated core structure for portable current transformers applicable for use with a through primary conductor, a fixed U-shaped core portion and a core portion comprising a plurality of laminations each bridging from one side'to the other of the U-shaped core portion and movable relatively to one another for closing the magnetic circuit, the alternate laminations of said last named core portion being hinged at points adjacent the opposite outer ends of said U-shaped portion.

2. In a core structure for current transformers applicable for use with a through primary conductor, comprising a rectangular core structure having two oppositely disposed winding legs of laminated magnetic material connected by two yokes, the alternate laminations constituting one of said yokes being movable relatively to one another and pivotally mounted adjacent the outer ends of the opposite windin le s.

3. In a current transformer, a core structure having two winding legs connected by two yokes to prowde a window adapted to accommodate a through primary conductor, said core structure being formed of layers of laminated steel, the alternate layers of the winding leg portions terminating adjacent the inner and outer boundaries, respectively, of the adjacent yoke portion to provide spaces for the overlap of the alternate laminations of the yoke portions with the laminations of the winding leg portions, the alternate laminations of one of said yoke portions being pivotally mounted at one end on pins .positioned beyond the outer boundary of the adjacent core leg.

4. In a current transformer, a core structure having two winding legs connected by two yokes to provide a window adapted to accommodate a through primary conductor, said core structure being formed of layers of laminated steel, the alternate layers of the winding leg portions terminating adjacent the inner and outer boundaries, respectively, of the adjacent yoke portion to provide spaces for the overlap of the alternate laminations of the yoke portions with the laminations of the winding leg portions, each of the laminations forming one of said yoke portions being movable relatively to other laminations and each extending from the inner edge of a winding leg along one side of the window and between laminations on the other winding leg to a hinge pin positioned outside of the window upon which alternate laminations are pivotally mounted.

5. In a current transformer, a core structure having two winding legs connected by two yokes to provide a window adapted to accommodate a through primary conductor, said core structure being formed of layers of laminated steel, the alternate layers of the winding leg portions terminating adjacent the inner and outer boundaries, respectively, of the adjacent yoke portion to provide spaces for the overlap of the alternate laminations of the yoke portions with the laminations of the winding leg portions, hinge pins located on opposite sides of saild core structure on the outside of said window adjacent corresponding ends of said winding leg portions, the alternate laminations forming one of said yoke portions being movable relatively to one another and pivotally mounted on opposite hinge pins and each extending between laminations of the winding leg adjacent its hinge pin to the inner edge of the other winding leg.

6. In a current transformer applicable for use with a through primary conductor, a rectangular core having two oppositely disposed winding legs connected by two oppositely disposed yokes to form a window through which the primary conductor may extend, said core comprising a plurality of layers of magnetic material, the portion of each layer constituting a part of one of said yokes being hinged for movement relative to the other layers of said yoke at a point exterior to said window and in line with the end of the portion of that layer constituting a part of the winding leg adjacent to the hinge point.

7. In a current transformer applicable for use with a through primary conductor, a rectangular core structure having two oppositely disposed winding legs connected by two oppositely disposed yokes to form a window through which the primary conductor may extend, said core comprising a plurality of layers of magnetic material, the portion of each layer constituting a part of one of said yokes being hinged at a point exterior to said window to swing from its magnet circuit closing position separately from the other layers, the portion of each layer constituting a part of the winding leg adjacent said hinged point terminating in abutting relation to the inner edge of said yoke portion, and the portion of each layer constituting a part of the other winding leg extending past the end of said yoke portion to align with the outer edge thereof.

8. In a current transformer applicable for use with a through primary conductor, a rectangular core structure having two oppositely disposed winding legs connected by two oppositely disposed yokes to form a window through which the primary conductor may extend, said core comprising a plurality of layers of magnetic material, the layers constituting one of said yoke portions being movable relatively to one another and individually hinged at one end to be movable between an open and a closed position, the winding leg part of each layer adjacent the hinged end of its associated movable yoke part ending in alignment with the inner edge of said movable yoke part when that part is in its closed position, and the winding leg part remote from the hinged end of said yoke part extending past the end thereof and terminating in alignment with the outer edge of said yoke 'part when that part is in its closed position, said core being assembled with alternate layers of said magnetic material positioned with the hinged ends of said yoke parts at opposite ends thereof.

EDWARD C. WENTZ. 

